Acceleration sensing switch



y 1954 H. N. SHOIKET ET AL 8 ,7

ACCELERATION SENSING SWITCH Filed May 17, 1952 -2 Sheets-Sheet l I VENTORS'. //'A/VA/ 40/1657 601444190 5 HA/A/AMAA/ W/AL/AM D. reorree BY W y 1954 H. N. SHOIKET ET AL ACCELERATION SENSING SWITCH Fild May 17, 1952 2 Sheets-Sheet 2 INVENTOR. #Qve M awo/zer EDPWJPD a. K/A/A/AMAA/ W/tA/AM 0 70rr Patented July 13, 1954 UNITED STATES PATENT OFFICE ACCELERATION SENSING SWITCH Delaware Application May 17, 1952, Serial No. 288,506

3 Claims.

This invention relates to acceleration sensing switches which close when vibratory or other accelerations exceed a predetermined value.

The invention comprises a housing containing a spring biased Weight which bears against a spring loaded contact member until vibratory or other movement of the weight free the contact member to permanently close the switch.

The purpose of the invention is to provide an acceleration sensing switch responsive to vibratory or other accelerations above a predetermined magnitude, occurring in a defined reference plane.

It is an object of the invention to provide an acceleration sensing switch for mounting on a movable mass that is subject to acceleration to automatically actuate controls terminating the motive forces.

It is an object of the invention to provide an acceleration sensing switch for mounting on a propulsive engine to automatically actuate electrical controls shutting down the engine when it becomes unbalanced.

It is an object of the invention to provide a compact, reliable acceleration sensing switch which can be readily manufactured and installed.

The purpose and objects of the invention will be apparent from the following description written with reference to the accompanying drawings, in which:

Figure 1 is a schematic sectional view of a turbo-jet engine mounted below a wing showing the placement of the acceleration sensing switch on the engine.

Figure 2 is a perspective View of the exterior of the acceleration sensing switch mounted on a section of the engine structure.

Figure 3 is a sectional view of the acceleration sensing switch of Figure 2 taken at 3-3.

Figure 4. is a sectional-perspective view of the acceleration sensing switch of Figure 2 taken on the broken surface planes 4-4.

Figure 5 is a sectional view of an embodiment of the invention.

Figure 6 is a sectional view of another embodiment of the invention.

Referring to Figure l, the inventive switch means as is mounted on the structure H of a turbo-jet engine 12 adjacent to the turbine rotor 13 or at some similar location, responsive to excessive radial acceleration caused by unbalanced conditions created upon the loss of turbine blades I 4, thereby energizing a relay in an electrical circuit E5 to operate a motor driven valve [6 stopping the flow of fuel to the engine 12 through the fuel supply line ll.

(Cl. ZOO-61.45)

The switch means IE oi the preferred embodiment, is contained within a housing I8 which is secured to the structure H by the fasteners I9, as noted in Figure 2.

The arrangement of the interior of the housing I3 is illustrated in Figures 3 and 4. Two fiat, non-intersecting, preloaded springs 20, 2|, extend outward from one side of the housing l8, their extending ends 22, 23 supporting a weight 24. Immediately below the serrated portion 25 on the bottom of the weight 24, is a slidable member 28, with complementary serrations 21, supported by a guide 28 secured to the base 29 of the housing 58.

The slider 26 on its extending end 30 has a U-shaped wire hook 3! which interfits with the extending closed tapered hooked end M of the wire spring 32 wrapped around and secured to an anchoring device 33 attached to the base 29 of the housing !8. Beyond the anchor 33 and located in the path followed by the spring end 41 when it is released, are open electrical contacts 34, 35, extending out from the back 36 of the housing 18 where electrical terminals 31, 38 are installed to receive the leads 39, '40 of the motor-driven valve circuit l5.

A hole is drilled and tapped in the base 29 and through the guide 28 to accommodate a set-screw 44 which is self-locking in any position. The set-screw 44 has a spherical end 45 which contacts the underside of the member 26 permitting slight corrections in its position on the guide 28 thereby insuring alignment of the complementary serrations 25 and 27.

The respective switch members remain in the positions illustrated in Figures 3 and 4 and as described above until the critical acceleration of the weight 24 and the preloaded springs 20, 21 is obtained, causing the weight to move free of the slider 26. The spring 32 is then free to move and the movement commenced does not terminate until the end 4| of the spring 32 strikes the contact 34 forcing and holding it against the complementary contact 35 closing the circuit i5, thereby energizing the actuating relays of the motors operating the valves [6.

In this manner the switch initiates a progression of functions cutting off the fuel supply to an engine which has become unbalanced due to the loss of some of its turbine blades or segments thereof, or by bearing failure.

The switch can be calibrated conveniently within limits to operate upon reaching a predetermined acceleration by the addition or removal of additive weights 42 located on the sides of the weight 24. The preloaded fiat spring a members 20, 2| are replaced readily by removing the fastening screws 43 and their replacement serves as another means of calibration for the new springs may have varying resilient characteristics.

Care must; be exercised in the design of the switch to make sure that accelerations, vibratory or otherwise, below the minimum predetermined. value do not trip the switch, and that resonant frequencies of the component parts of the switch do not occur within the normal operating range of frequencies of the equipment onwhich the. switch is mounted.

Figures 5 and 6 show embodiments: cethe in;- vention wherein the same cooperation of elements is involved, but their arran ement, within the housing I8 is modified.

The embodiment of Figure 5 utilizes a weight d li which is biased upward against a slider-contact 4.5 by; a coiled springs-6. slider-contact 45 into, an abutting relationshipwith, the contact 48, when the. weight 44: vibrates with sufficient acceleration releasing theslider 45'. Qtherfeatures include, aguide; 4 9 to insure that the weight M will. be only responsive;toivibrations in a radialplane and an access hole 5!l-to aecommo ate a tool (not, shown) for manually reset tingthe slider-contactdi The. embodiment, of Figure 6, comprises a weight 5| attached to acompressed2 coil spring 5 2 and biased against a slider 53, supported by they rest 54. When the unbalanced condition of the engine 12 causes the weight 5t to vibrate-with,

suficient. magnitude, the, slider 53 is withdrawn from beneath the weight; 54-. by: the-- spring 55 closing the contacts 5.6,- 51.

These embodiments can be: manufactured, as-

sembled and installed veryreadilytoserve their important, function of; automatically-actuating relays that indirectly shut down. an engine which,

has become unbalanceddue to: theloss. of turbine blades orsegmentsthereof.

Having now particularly described andascertamedthe nature of my invention, andiin what: manner the same isto; beperformed; I declare that whatl claim is:

1, An; automatic switch-to actuatean electrical" circuit when vibrationsexceeding a given; magni- A spring 41-, pulls the weight, a spring operated plunger held in a retracted position by the said weight and said preloaded spring, the plunger-spring attached to the said housing and hooked under tension to the said plunger, and spaced electrical contacts mounted in the housing within the striking movement of the said plunger-spring when it is freed as the said plunger is released by the said weight undergoing vibration of a predetermined magnitude.

2. automatic switch to actuate an electrical circuitwhen vibrations exceeding a given magnitude are'transmitted to the switch, comprising a housing; av mass; resiliently supported within the housing-F pheloaded leaf springs supporting the mass and controlling its movement, a spring operated plunger held in a retracted position by the mass and preloaded spring, the plunger-spring attached to the housing and hooked under tension to the said plunger, and spaced electrical contacts mounted in the. housing. within the striking, movement of the said plunger-spring.

when-.itis freed as, thesaid plunger islreleased by the said weight undergoin vibration. of a predetermined magnitude.

3.- An automatic switch to actuate an electrical. circuittwhen vibrations exceeding; a. given magni-- tude aretransmittedto the switch, comprising a v housing, a'weigh-t' within the said housing, preloaded springs. supporting the weight. andv controlling; its movement, a spring operatedplunger hel-din arretracted, positionibyt the: mass and pre- References Cited in. the file of this patent.-

UNITED. STATESTPA'I'ENZISJ Number Name Date 915,249 Stratton Mar; 16, 1909 1,'53 5',24(l Morris Apr. 28,1925 1,626,921 Douglas May 3, 1927 2188,14 1 Eytman Jan. '23, I940 2,488,739 'Printz Nov. 22,1949 7 2,551,752" Mathisen' May 8,. 1951 2,581,078. Corfield .Jan. 1,1952 2,585,749 Lorenzo Feb. 12; 1952. 

